TETRAMEEOUS PLANT-BEETLES. 177 



Cassida proper. 



nigripes, Oliv.; leDgtb one-fourth inch or less ; dull red, with three obscure black dote on each ely- 

 tron, in a triangle ; puncto-striate. The pallida, Herbst, is probably a pale variety of this. 



bivittata, Say ; length two-tenth inch ; thorax dull red ; elytra yellow, with a black suture and two 

 black stripes on each ; puncto-striate. 



thoracica, Boh.; length three-tenth inch ; pale green, region of the scutellnm obscure brownish ; ir- 

 regularly punatate. 



Coptocycla. 



aurichalcea, Fab.; length less than ODe-foorth inch ; golden yellow, pale yellow after death, puncto- 

 striate. 



clavata, Fab.; length more than one-fourth inch ; uneven, dark brown ; margin of thorax and middle 

 and tip of margin of elytra, pale transparent. 



guttata, Oliy.; length less than one-fourth inch ; varying from pale brown to blackish brown, some- 

 times spotted with yellow; the whole margin, except the shoulders of elytra, pale transparent. 



purpurata, 'Bob.; less than one-fourth inch; brownish red with a lateral triangular transparent 

 patch ; rare. 



Section IV. TBIMEBA. 



Apparently three joints in all the tarsi, except the Erotylidce, which hav» four or five; the jointt 

 dilated and bruth-like beneath, with the penultimat* usually bilobed. 



This, like the other primary sections of the Coleoptera, is based upon 

 the apparent number of joints in the tarsi. We have stated in the in- 

 troductory part of this treatise that the highest, and what may there- 

 fore be called the normal or typical number of joints in the feet of the 

 Coleoptera, is five, and that whenever there appears to be a lesser num- 

 ber the rudiments of the deficient joints, or a part of them, can usually 

 be detected by close inspection. The present, or trimerous section, is 

 less perfect or more exceptional in proportion to the number of the spe- 

 cies, than any of the preceding sections, that is to say, a considerable 

 number of genera aud species which require to be associated with the 

 trimerous beetles in consideration of their general structure, have four 

 distinct joints in their tarsi, besides the indistinct rudiment of the miss- 

 •ing and penultimate joint. 



The anteunaj are almost always clubbed at the end and the tarsi are 

 dilated, bilobed, aud with a brush of hairs on the under side. The first 

 of these characters allies them to the club-horned scavengers and dis- 

 tinguishes them from the Chrysomelidie, whilst the latter character 

 allies them to the last named family and at the same time distinguishes 

 them from the Clavicornes proper. The great majority of them are re- 

 markable for the very wide terminal joint of the maxillary palpi. They 

 are almost always of small or moderate size. 



This section is much smaller than the others, and contains but two 

 tribes, which bear but little resemblance to each other in form, and are 

 wholly unlike in their habits. 



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